Hubble's Final Fix-It Flight Almost Never Was

Astronauts Steven Smith, and John Grunsfeld, appear as small figures in this wide scene photographed during an STS-103 extravehicular activity (EVA) to service the Hubble Space Telescope in December 1999.Credit: NASA.

CAPE
CANAVERAL, Fla. - The stage is set for NASA?s last trek to the Hubble Space
Telescope, with seven astronauts and two space shuttles waiting in the wings to
fly a risky mission that almost never was.

The mission
is STS-125, NASA?s fifth and final
Hubble servicing flight, and is poised to launch toward the iconic space
telescope on May 11 at 2:01 p.m. EDT (1801 GMT) aboard the space shuttle
Atlantis. Veteran shuttle commander Scott Altman is leading the charge for the
11-day mission, which includes five tricky spacewalks to extend Hubble?s vision
and life through at least 2014.

But just
reaching this point, with Atlantis days from launch, has been a Herculean feat
for NASA given that the agency canceled the mission outright in 2004. Sending
a shuttle to Hubble, beyond reach of the International Space Station,
carried too great a risk in the wake of the tragic loss of the shuttle Columbia
and its crew, the agency said then.

?It was
about the most devastating day that I?ve ever had in my entire life,? Hubble?s
program scientist David Leckrone said recently while reflecting on that time.
?And I think that was true for the entire Hubble team.?

The
announcement sparked outcry from scientists and the public, not to mention
disappointment in Altman and his crew.

?As a
certified ?Hubble hugger,? that hit me like a two-by-four,? said the mission?s
lead spacewalker John Grunsfeld, who is making his third trip to Hubble and
fifth spaceflight. ?I just couldn?t believe that we would prematurely make that
decision.?

NASA now
has a second space shuttle - the Endeavour orbiter - standing
by as a rescue ship if Atlantis? crew runs into serious trouble in space,
but it was a long and winding road to get to that point.

Hubble?s
historical fixes

NASA launched
the Hubble Space Telescope in 1990 to the cheers of astronomers the world over
eager to use its camera eye to peer deep into the universe. It was built by
NASA and the European Space Agency specifically so astronauts could perform
maintenance and upgrades.

But after
its first two months of tests, the initial images from Hubble were a blurry
disappointment. A slight flaw in the telescope?s main mirror ? barely the width
of a human hair ? fouled the observatory?s vision and some critics later
?declared Hubble a national disgrace,? said Ed Weiler, NASA's associate
administrator for science missions, in a recent briefing.

In 1993,
NASA sent another shuttle up to Hubble, where astronauts added corrective
lenses - essentially glasses - to sharpen its vision. The result was crystal
clear: 16 years of stunning
cosmic photos followed.

?Some
called it the miracle-in-space mission,? Weiler said. ?And of course the rest
is history.?

Since that
first orbital fix, astronauts returned to Hubble three more times; in 1997,
1999 and 2002. But the 2003 loss of Columbia shook the servicing schedule to
its core.

?Servicing
was originally designed to occur approximately every three years, but it?s been
over seven years now,? said Hubble project manager Preston Burch, of NASA's
Goddard Space Flight Center in Greenbelt, Md. ?We have a considerable
accumulation of maintenance items that need to be taken care of.?

At first,
NASA stuck by its 2004 decision to leave Hubble to its un-serviced fate. By
2005 the space agency, in response to pressure from the public and scientific
community, drew a plan to send a robot ? instead of astronauts ? to perform the
service call.

Hubble
overhaul resurrected

But it was
in September 2006, after the robotic option was deemed untenable, that NASA
backtracked and officially announced its plan to send astronauts to save Hubble
one last time.

The
reasoning was clear. To address the risk posed by Atlantis? inability to ferry
its crew to the International Space Station if the shuttle is damaged and
cannot return home, NASA would ready Endeavour as a rescue ship. Endeavour a
small crew of four are primed to launch within a week of a declared emergency
to retrieve the Atlantis astronauts.

?It?s a
very low probability of an event, but I?m glad that there?s a relatively robust
plan to deal with it if it did happen,? commander Altman said in a NASA interview.

Atlantis
cannot reach the station from Hubble because the space telescope flies higher
(about 350 miles up versus the station?s 220-mile orbit) and in a different
inclination, or tilt with respect to the Earth?s equator.

?I think of
Hubble as a rollercoaster,? Weiler said, adding that one thing has become clear
in the space telescope?s storied past. ?Everybody loves Hubble now.?